Spark plug



Feb. 28, 1950 Gf H, PALMER 2,498,822

SPARK PLUG .Filed May 11, 1945 f1; l/6 f IN V EN TOR.

affffzm er Patented Feb. 28, 1950 UNl'lfnDv .si-Ares 2,498,822 v H f 7 vSPARK PLUG y Gilbert 11,-Barmer, Ardinmrweine. v applicateurMay 11, 1945,..seriatnmsaalss v 1. claim. (c1. usarse) "The present inventionrelates to new and' use-l "fui-improvements in sparkplugs of agtype' de -sif.:ned"for use in internal combustion engines.

An important object of the present invention is to provide a spark plug of this type embodying means for intensifying the current through the provision of gaps in the conductor leading to the electrodes at the inner end of the plug and across which a firing current must jump.

A further object of the invention is to provide upper and lower spark gaps in the spark plug and enclosing the upper gap in a transparent body by means of which the spark between the upper gaps may be observed to determine whether the plug is properly functioning without necessitating a removal of the plug from the engine.

A further object is to provide a device of this character of simple and practical construction, which is efficient and reliable in operation, relatively inexpensive to manufacture and otherwise well adapted for the purposes for which the same is intended,

Other objects and advantages reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawing forming part hereof, ywherein like numerals refer to like parts throughout, and in which:

Figure l is a longitudinal sectional view, and

Figures 2 and 3 are transverse sectional views taken respectively on lines 2-2 and 3-3 of Figure 1.

Referring now to the drawing in detail, wherein for the purpose of illustration 1 have disclosed a preferred embodiment of the invention, the numeral 5 designates the body of the spark plug constructed of suitable insulation material having a reduced extension 8 at its lower end formed .with external threads 'I for threadedly connecting the `spark plug in the usual spark plug opening of the cylinder of an internal combustion engine in a manner well known in the art.

A pair of electrodes 8 have one end embedded in the extension 5 and extend vertically therein at diametrically opposite sides of the extension and with a portion of the sides of the electrodes exposed at the sides of the extension between the threads 1, as indicated more clearly in Figure 3 of the drawing, whereby to contact the engine block to provide a ground for the plug.

The lower ends of the electrodes 8 extend below the extension 6 and project inwardly toward each other, as indicated at 9, and slightly spaced from each other and also spaced below the lower end of an electrode I8 extending axially through the body 5'- and vthe-extension lIi to lform asparkcgap attheiower end 'of theplug.

Theupper-portion of thelelectrode 'I8 isiormed with ings Ill-embedded in the body 5 toanchor the electrode in the body.

The upper end of the electrode I0 extends upwardly above the body 5 and is formed with an enlarged head I2.

The head I2 is positioned in a chamber I3 formed in the lower portion of an elongated cap I4 preferably of frusto-conical shape and constructed of glass, or other suitable transparent insulation material.

The bottom of the cap I4 is fused, welded, or otherwise suitably secured to the top of the body 5, as indicated at I5.

The cap I4 is formed with a bore I6 in which a conductor I1 is positioned having a head I8 at its lower end positioned in the chamber I3 and spaced above the head I2 of the electrode I8.

The upper end of the conductor I'I is threaded and the conductor is maintained in spaced rela.- tion from the sides of the bore I6 by means of a spacing sleeve or bushing I9 in the upper end of the bore.

A nut 20 is threaded on the upper end of the conductor II for securing an ignition wire 2| thereto above a lock nut 22 threaded on the conducter for securing the latter in adjusted position in the cap I4 to regulate the gap between the heads I2and I8.

In the operation of the device, the :current passing through the spark plug must jump the gap between the heads I2 and I8 whereby to intensify the current before reaching the gap between the electrodes 9 and I0 at the lower end of the plug.

The gap between the heads I2 and I8 may be adjusted by means of the nuts 28 and 22 and the spark, jumping between the heads I2 and I8, may be observed through the transparent cap I4 without necessitating a removal of the spark plug from the engine to thus determine whether the plug is properly firing.

If desired the bod7 5 and the threaded extension may also be formed of transparent material 'to permit inspection into the cylinder to observe whether the lower spark gap is properly functioning.

l It is believed the details of construction, manner of operation and advantages of the invention will Abe readily understood from the `foregoing without', further detailed explanation..

4iinderstc'iod that various changes may -be'm'ade in While' I have herein. vshown and described a ed embodiment of my invention,it:w1ll 'be afxed in the sides of the lower portion of the body and terminating in spaced relation to the.

lower end of the central electrode, a riser of transparent material of upwardly tapering form secured at its lower portion tothe top of the main body, said riser having an opening in the lower portionthereof for receiving the upper end of the central electrode, said riser being formed with an ,opening extending upwardlyrfrom the rstmentioned opening and through thetop of the riser, a spacing sleeve in the upper portion of the riser,

.asupplemental Icentral electrode extending downwardly through the sleeve and terminating within the first mentioned opening in spaced relation to the upper end of the central electrode, and means for adjusting and locking the supplemental electrode longitudinally in the riser and with respect to the central electrode.

GILBERT H. PALMER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,453,039 Chinsky et al Apr. 24, 1923 1,454,442 Howard May 8, 1923 1,468,970 Leonard Sept. 25, 1923 1,488,526 Butler Apr. 1, 1924 1,783,525 Stewart Dec. 2, 1930 1,848,065 Rabezzana Mar. 1, 1932 1,941,279 Sharpnack Dec. 26, 1933 2,208,030 Holmes July 16, 1940 

